Nitro compounds are commonly utilised as a raw material for medicines, agricultural chemicals, dyes, solvents and explosives, a raw material for amino compounds, and the like. Nitration of hydrocarbons is generally conducted by a nitric acid process which employs a mixed acid (a mixture of nitric acid and sulfric acid). However, the nitric acid process requires a strong acid of high concentration in a large amount. Besides, since the nitration reaction is exothermic, it is difficult to improve its reaction operability. Furthermore, the nitric acid process by-produces large amounts of nitrogen oxides, which cause environmental pollutions and thus have to be treated in a proper manner.
As a nitration process, use of N.sub.2 O.sub.5 and ozone in the presence of an iron catalyst has been suggested for nitration of aromatic compounds (e.g. toluene) and alicyclic compounds (e.g. adamantane). Due to the use of NO.sub.3 as a reactant, this nitration process proceeds smoothly at a lower temperature. However, a catalyst should be incorporated in order to increase the reaction rate, and additional equipment such as an ozone generating apparatus should be installed for the generation of ozone.